Matt 1:21 21 And she shall bring forth a son, and thou shalt call his name Jesus: for he shall save his people from their sins. This is a Promise of something that must be done, its a promised Salvation of a very specific people. Rom 4:16 Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, Yes, the seed here in this verse and the his people in the Matt 1:21 verse are the same. The saving is the same, in Rom 4:16, the promise is speaking about Salvation. Lk 2:30-32 30 For mine eyes have seen thy salvation, 31 Which thou hast prepared before the face of all people; 32 A light to lighten the Gentiles, and the glory of thy people Israel. Lk 1:68-77 68 Blessed be the Lord God of Israel; for he hath visited and redeemed his people, 69 And hath raised up an horn of salvation for us in the house of his servant David; 70 As he spake by the mouth of his holy prophets, which have been since the world began: 71 That we should be saved from our enemies, and from the hand of all that hate us; 72 To perform the mercy promised to our fathers, and to remember his holy covenant; 73 The oath which he sware to our father Abraham, 74 That he would grant unto us, that we being delivered out of the hand of our enemies might serve him without fear, 75 In holiness and righteousness before him, all the days of our life. 76 And thou, child, shalt be called the prophet of the Highest: for thou shalt go before the face of the Lord to prepare his ways; 77 To give knowledge of salvation unto his people by the remission of their sins, All whom receive a Knowledge of remission of their sins are the His People of Matt 1:21 and the seed of Rom 4:16. Notice the mention of our Father Abraham in vs 73 Abraham is the Father of us all who Believe Rom 4:16 Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, Now Salvation is sure to all the seed, it is by Faith that it should be by Grace. So Faith is conditioned by Grace, and not the other way around as the false christian world would tell us. If the promise of eternal salvation or eternal inheritance were conditioned upon those of the seed having faith, then how could the promises be sure to them ? But if Faith is a product of Grace, then we can understand how the promises are sure to all the seed. For the seed believes through or by Grace Acts 18:27 27 And when he was disposed to pass into Achaia, the brethren wrote, exhorting the disciples to receive him: who, when he was come, helped them much which had believed through grace: Because the seed had been ordained to Eternal Life or Inheritance Acts 13:48 48 And when the Gentiles heard this, they were glad, and glorified the word of the Lord: and as many as were ordained to eternal life believed And as long as Grace Reigns, faith will be empowered, so all the seed is being kept by the Power and Grace of God through Faith 1Pet 1:5 5 Who are kept by the power of God through faith unto salvation ready to be revealed in the last time. That is the Power of God [Grace Reigning] keeps us in the Faith, Grace it is we believe by Acts 18:27, so Grace keeps us believing, if we be of that Holy Seed ! Those who teach that Salvation is a condional offer to all, they are false teachers and do not understand that Salvation is a Promise to all of a certain seed !